Captive Surrender by Linda Mooney

An elite member of the Psi Police Corps, Maurra instinctively goes to the alien's defense when she sees him attacked by a group of vicious Kronners. Her attempt fails and Maurra wakes, naked, in a cell on a Kronner ship—her psionic abilities rendered useless.

She discovers that the alien, Safan, was also kidnapped and is held in the cell next to hers. They are both horrified when a disembodied voice tells them their lives will be spared on one condition: that they have sex for the amusement of their "audience".

In a situation with no escape, Maurra and Safan reluctantly obey and are surprised to find that their intimate performance opens them to new levels of pleasure. But when their captors reveal the next level of their sick plan, Maurra and Safan grow desperate to escape—together.